The isotope technetium-99 (99Tc ,�max: 293.7 keV, half-life: 2.1 x 105 years) is a major product of U-235 fission and is present in spent fuel as well as in the radioactive waste stored in underground tanks at Hanford and Savannah River.  The complex redox activity of 99Tc poses a problem for closing the fuel cycle, remediation of waste tanks and immobilization of 99Tc found in the environment. Polyoxometalates (POMs), nanometer-sized metal oxide clusters, and polyphosphates incorporate 99Tc into their vacancies and stabilize specific oxidation states depending on the coordination environment of the metal oxide vacancies or defects.  Studies that include X-ray crystallography, X-ray Absorption Spectroscopy, electrochemistry, multinuclear NMR in combination with theoretical methods, result in identification of features of POM and polyphosphate binding sites that enhance stability of low valent 99Tc.  POMs, themselves, can be photoactivated in the presence of 2-propanol to transfer electrons to 99TcO4- and stabilize the low valent 99Tc.

Speciation of Technetium-99 in the presence of nanometer-sized metal oxides

243rd National Meeting (2012)

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